1. Field of the Invention
The present invention relates to computer-controlled locking devices. In particular, the present invention relates to a system and method for controlling and monitoring the release o a key from a remote location.
2. Description of the Related Art
In various situations it is desirable to secure an access key in one location, and to control the release of the access key from a remote location to an individual entitled to access. U.S. Pat. No. 4,567,741 to the applicant discloses a security key holder system that enables this function to be performed. The system comprises an encoder unit and a decoder unit. The decoder unit has an access key socket for securing an access key (by the coded portion of the access key), and a secondary key socket for the insertion of a secondary key.
The access key can be rotated and removed from the access key socket only upon the substantially simultaneous occurrence of two events. The first event is the transmission of a key release signal from the encoder unit to the decoder unit. The key release signal activates a solenoid inside the decoder unit, thereby allowing the secondary key to be rotated. The second event is the insertion and rotation of a secondary key in a secondary key socket. Once the secondary key has been rotated, the access key can be rotated and removed.
The decoder unit is typically mounted in a fire truck or a public location, and the encoder unit is typically located at a remote dispatcher station such as a fire station. The system typically serves to secure a master access key to one or more buildings, and to release the key in an emergency situation such as a fire.
The release signal is transmitted to the decoder unit in one of two ways. The first is via the two-way radio system commonly used by fire and police departments, and is used primarily when the decoder unit is mounted within a fire truck or police car. The decoder unit is merely connected to the receiver of the existing two-way radio of the vehicle. The second is via a telephone network. This second method of transmitting the release signal is generally used when the decoder unit is mounted in a fixed location such as an office building.
The system provides a high level of security against the unauthorized release of the access key, since the access key can only be removed by one in possession of a secondary key, and only when the key release signal is received. To further protect against unauthorized releases, each individual decoder unit is assigned a unique release signal. To protect against forced entry, the decoder unit has a housing composed of hardened steel, and the access key is surrounded by a steel barrier to protect against the use of forcing tools.
Although the system described above is more than adequate for the applications for which it was designed, there exists a need to provide a higher level of protection against unauthorized key releases in certain situations. For example, the system described above may not provide the level of security desired for securing a key that provides access to an art museum. It is an object of the present invention, therefore, to provide a security key holder suitable for applications for which the risk of an unauthorized release is inordinate.